Reversal of hyperreactivity to bradykinin in renal hypertensive rats.
Increased blood pressure responsiveness to bradykinin in comparison with other vasodilator agents was demonstrated in rats with long-term one-kidney and two-kidney, one clip hypertension. In the present study, we analyzed the reactivity to intra-aortically injected bradykinin in unanesthetized one-kidney, one clip hypertensive rats during the control period and 1, 5, and 8 hours after reversal of hypertension after removal of the renal artery constriction. One and 5 hours after unclipping the renal artery, the mean blood pressure decreased markedly (from 195 +/- 7 to 124 +/- 8 and 145 +/- 9 mm Hg, respectively), whereas the hyperreactivity to bradykinin reverted only slightly, and the responses to nitroprusside remained unchanged. In another group of hypertensive rats examined 8 hours after unclipping (pressure decreased from 192 +/- 4 to 143 +/- 8 mm Hg), the hyperreactivity to bradykinin had partially reverted. Significantly larger doses of bradykinin were necessary to produce the same decrease in blood pressure when compared with the control period (16.4 +/- 2.0 vs. 7.2 +/- 1.2 ng). The same degree of reversal of hyperreactivity to bradykinin was observed when the blood pressure of hypertensive rats was reduced (from 207 +/- 8 to 143 +/- 5 mm Hg) during 1 hour by hydralazine injection. Complete reversibility of bradykinin hyperreactivity was produced by nitroprusside infusion (from 201 +/- 13 to 142 +/- 10 mm Hg).(ABSTRACT TRUNCATED AT 250 WORDS)
Camacho
A A
AA
Department of Pharmacology, Faculty of Medicine of Ribeirão Prêto, University of São Paulo, Brazil.
Salgado
M C
MC
Krieger
E M
EM
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D001920:Bradykinin / Q000494:pharmacology*; D003250:Constriction; D004305:Dose-Response Relationship, Drug; D006830:Hydralazine / Q000494:pharmacology; D006977:Hypertension, Renal / Q000503:physiopathology*; D008297:Male; D009599:Nitroprusside / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012077:Renal Artery / Q000503:physiopathology; D014665:Vasodilator Agents / Q000494:pharmacology
D014665:Vasodilator Agents; D009599:Nitroprusside; D006830:Hydralazine; D001920:Bradykinin